Method and unit for transferring a product on an intermittent packing machine

ABSTRACT

On a packing machine, pockets on a conveyor are fed in steps through a transfer station; and at least one product is transferred to/from a pocket on the conveyor when the pocket is arrested at the transfer station during a pause between two successive steps; before the product is transferred, the pocket is moved with respect to the conveyor to set the pocket to a given transfer position at the transfer station.

The present invention relates to a method and unit for transferring a product on an intermittent packing machine.

The present invention may be used to advantage in an intermittent automatic cigarette packing machine, to which the following description refers purely by way of example.

BACKGROUND OF THE INVENTION

Cigarette packing machines are traditionally “intermittent” machines, i.e. the packing conveyors are operated intermittently (or “in steps”), in which a pause, during which the packing conveyor pockets are stationary, alternates cyclically with a conveying step, during which the packing conveyor pockets advance a given distance. On an “intermittent” packing machine, groups of cigarettes are transferred between two successive packing conveyors during the pause.

An intermittent cigarette packing machine normally comprises a number of packing wheels with peripheral pockets for receiving and conveying groups of cigarettes. The groups of cigarettes for packing are fed gradually through the packing machine, and are transferred from one packing wheel to the next at a transfer station defined at the point of tangency between the two wheels. At each transfer station, two pockets of the two packing wheels are aligned (transversely or longitudinally) and positioned facing each other during the pause between one conveying step and the next, to allow a push member to transfer a group of cigarettes from the releasing pocket to the receiving pocket.

In all known intermittent packing machines, the pockets of each packing wheel are connected rigidly to, and so perform no movement with respect to, the packing wheel. The packing wheels are obviously so designed and located that a releasing pocket is always aligned facing the corresponding receiving pocket at the transfer stations, to allow transfer of a group of cigarettes from one pocket to the other.

Though cheap and easy to produce, packing wheels of the above type are extremely rigid in terms of positioning, and also have the drawback of entailing considerable design complications to transfer more than one group of cigarettes at a time between two adjacent packing wheels.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a method and unit for transferring a product on an intermittent packing machine, and which are designed to eliminate the aforementioned drawbacks and, in particular, are cheap and easy to implement.

According to the present invention, there are provided a method and unit for transferring a product on an intermittent packing machine, as claimed in the attached Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:

FIG. 1 shows a schematic front view of an intermittent cigarette packing machine in accordance with the present invention;

FIG. 2 shows a schematic plan view of the intermittent packing machine in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

Number 1 in FIG. 1 indicates as a whole a packing machine for producing rigid, hinged-lid packets 2 of cigarettes. Each packet 2 of cigarettes comprises a group 3 of cigarettes normally containing twenty cigarettes 4; an inner sheet 5 of foil packing material enclosing group 3 of cigarettes; and a blank 6, which is folded about group 3 of cigarettes, enclosed in inner sheet 5 of packing material, to form a rigid, hinged-lid outer container. A U-folded collar 7 is inserted inside an open top end of the container to engage an inner surface of the lid when the lid is in a closed position.

Packing machine 1 comprises a frame 8 (shown schematically in FIG. 1), which supports a number of work stations 9 located along a production line 10 and each comprising a respective number of operating devices. More specifically, packing machine 1 comprises eight work stations 9: a forming station 9 a for forming groups 3 of cigarettes 4; a feed station 9 b for supplying inner sheets 5 of packing material; a folding station 9 c for folding inner sheets 5 of packing material about groups 3 of cigarettes 4; a feed station 9 d for supplying collars 7; a folding station 9 e for folding collars 7 about groups 3 of cigarettes 4 and over the folded inner sheets 5 of packing material; a feed station 9 f for supplying blanks 6; a folding station 9 g for folding blanks 6 about groups 3 of cigarettes 4 and over the folded inner sheets 5 of packing material; and a drying station 9 h for drying packets 2.

The main operating devices of each work station 9 will be described as shown in FIGS. 1 and 2. In actual fact, each work station 9 comprises additional operating devices which the schematic nature of the accompanying drawings does not allow to be shown in detail.

Forming station 9 a for forming groups 3 of cigarettes 4 comprises a hopper 11 having three outlets for simultaneously feeding three groups 3 of cigarettes 4 to three pockets 12 of a forming conveyor 13. Forming conveyor 13 comprises an octagonal (polygonal) drum 14 which rotates intermittently (or “in steps”) about a horizontal axis of rotation 15 perpendicular to the FIG. 1 plane. Drum 14 supports four groups of pockets 12, each comprising three pockets 12. In each group of pockets 12, a central pocket 12 is fixed with respect to drum 14, while the other two lateral pockets 12 are hinged to drum 14 to rotate, with respect to drum 14 and under the control of a cam actuating system (not shown), about respective axes 16 parallel to axis of rotation 15. As stated, drum 14 rotates intermittently (or “in steps”) about axis of rotation 15, and, for each conveying step, rotates 90° (i.e. by an angle equal to a full turn divided by the number of groups of pockets 12).

Feed station 9 b comprises a feed device 17, which receives a strip 18 of foil, unwound gradually off a reel (not shown), and detaches from strip 18 of foil a succession of inner sheets 5 of packing material which are fed individually (i.e. one at a time) to folding station 9 c.

Folding station 9 c comprises a packing conveyor 19 having two arms 20, each rotating intermittently (or “in steps”) about an axis of rotation 21 parallel to axis of rotation 15. Arms 20 support four groups of pockets 22, each comprising three pockets 22. Each group of pockets 22 comprises a central pocket 22 and two lateral pockets 22 fixed with respect to the corresponding arm 20. As stated, each arm 20 rotates intermittently (or “in steps”) about axis of rotation 21, and, for each conveying step, rotates 90° (i.e. by an angle equal to a full turn divided by the number of groups of pockets 22). It is important to note that packing conveyor 19 has two arms 20, each of which supports two groups of three pockets 22 each, and rotates about axis of rotation 21 intermittently and out of phase with respect to the other arm 20, so that, while the two groups of pockets 22 of one arm 20 are stationary, the other two groups of pockets 22 of the other arm 20 may be moving. Obviously, the phase difference between the two movements of the two arms 20 must be such as to avoid any mechanical interference between the two arms 20.

Folding station 9 c also comprises a fixed folding member, which defines a packing station, is located, in a fixed position, close to packing conveyor 19, and provides for folding inner sheets 5 of packing material about groups 3 of cigarettes 4. More specifically, the fixed folding member comprises helical folding devices.

Feed station 9 d comprises a feed device 23 for successively detaching collars 7 from a strip 24 of collars 7 unwound off a reel (not shown), and for feeding collars 7 individually (i.e. one at a time) to folding station 9 e.

Folding station 9 e comprises a packing conveyor 25 having two arms 26, each rotating intermittently (or “in steps”) about an axis of rotation 27 parallel to axis of rotation 15. Arms 26 support four groups of pockets 28, each comprising three pockets 28. In each group of pockets 28, a central pocket 28 is fixed with respect to arm 26, while the other two lateral pockets 28 are hinged to arm 26 to rotate, with respect to arm 26 and under the control of a cam actuating system (not shown), about respective axes 29 parallel to axis of rotation 27. As stated, each arm 26 rotates intermittently (or “in steps”) about axis of rotation 27, and, for each conveying step, rotates 90° (i.e. by an angle equal to a full turn divided by the number of groups of pockets 28). It is important to note that packing conveyor 25 has two arms 26, each of which supports two groups of three pockets 28 each, and rotates about axis of rotation 27 intermittently and out of phase with respect to the other arm 26, so that, while the two groups of pockets 28 of one arm 26 are stationary, the other two groups of pockets 28 of the other arm 26 may be moving. Obviously, the phase difference between the two movements of the two arms 26 must be such as to avoid any mechanical interference between the two arms 26.

Folding station 9 e also comprises a fixed folding member, which defines a packing station, is located, in a fixed position, close to packing conveyor 25, and provides for folding collars 7 about groups 3 of cigarettes 4 and over the folded inner sheets 5 of packing material. More specifically, the fixed folding member comprises helical folding devices.

Feed station 9 f comprises a feed device 30 for withdrawing blanks 6 successively from the bottom of a hopper 31 and feeding blanks 6 individually (i.e. one at a time) to folding station 9 g. Feed device 30 comprises a pickup drum 32 having a number of suction seats 33 (only one shown in FIG. 1) for withdrawing blanks 6 from the bottom of hopper 31 and feeding the blanks to an intermediate suction drum 34. Intermediate drum 34 feeds blanks 6 through a gumming station, where gum is deposited on the inner face of each blank 6 by a gumming drum 35, and then releases the gummed blanks 6 onto a feed drum 36. Feed drum 36 feeds blanks 6 through a pre-folding station, where each blank 6 is folded along preformed longitudinal fold lines by a pre-folding member 37, and then feeds the gummed, pre-folded blanks 6 successively (i.e. one at a time) to folding station 9 g.

Feed drum 36 has a number of suction seats 38, each of which engages a central portion of a blank 6 and is the same shape and size as a group 3 of cigarettes. Pre-folding member 37 is a drum with three lobes, which, as they rotate, fold the lateral portions of each blank 6 against the respective suction seat 38.

Folding station 9 g comprises a packing conveyor 39 having two arms 40, each rotating intermittently (or “in steps”) about an axis of rotation 41 parallel to axis of rotation 15. Arms 40 support four groups of pockets 42, each comprising three pockets 42. In each group of pockets 42, a central pocket 42 is fixed with respect to arm 40, while the other two lateral pockets 42 are hinged to arm 40 to rotate, with respect to arm 40 and under the control of a cam actuating system (not shown), about respective axes 43 parallel to axis of rotation 41. As stated, each arm 40 rotates intermittently (or “in steps”) about axis of rotation 41, and, for each conveying step, rotates 90° (i.e. by an angle equal to a full turn divided by the number of groups of pockets 42).

It is important to note that packing conveyor 39 has two arms 40, each of which supports two groups of three pockets 42 each, and rotates about axis of rotation 41 intermittently and out of phase with respect to the other arm 40, so that, while the two groups of pockets 42 of one arm 40 are stationary, the other two groups of pockets 42 of the other arm 40 may be moving. Obviously, the phase difference between the two movements of the two arms 40 must be such as to avoid any mechanical interference between the two arms 40.

Folding station 9 g also comprises a fixed folding member, which defines a packing station, is located, in a fixed position, close to packing conveyor 39, and provides for folding blanks 6 about groups 3 of cigarettes 4 and over the folded inner sheets 5 of packing material. More specifically, the fixed folding member comprises helical folding devices.

Drying station 9 h comprises a linear drying conveyor 44, in turn comprising three parallel conveyor belts 45 defining three parallel horizontal paths for packets 2 of cigarettes.

Downstream from linear drying conveyor 44, an output conveyor 46 receives packets 2 of cigarettes from the three conveyor belts 45, and feeds packets 2 of cigarettes along a single output path comprising a straight vertical initial portion at the outlets of the three conveyor belts 45, a curved intermediate portion, and a straight downward-sloping end portion. Output conveyor 46 comprises a box body 47, along which runs an endless conveyor belt 48 having a number of projections (not shown) for pushing packets 2 of cigarettes. Packets 2 of cigarettes are held contacting conveyor belt 48 by a number of fixed rails 49 (only one shown in FIG. 1).

Operation of packing machine 1 will now be described with reference to the packing operations performed successively on a set of three groups 3 of cigarettes.

At forming station 9 a, drum 14 of forming conveyor 13 advances one step (defined by a 90° clockwise rotation) to position a group of three pockets 12 in front of the three outlets of hopper 11; when the group of three pockets 12 is arrested in front of the three outlets of hopper 11, the three pockets 12 are aligned with one another, and each pocket 12 is positioned axially facing and aligned with an outlet of hopper 11. At this point, a pusher 50 (FIG. 2), having three parallel push members, transfers the three groups 3 of cigarettes from the outlets of hopper 11 to the three pockets 12. Pusher 50 performs a back and forth movement, comprising a forward stroke and a return stroke, both parallel to axis of rotation 15, while the three pockets 12 are stationary in front of the three outlets of hopper 11.

After three successive conveying steps (each defined by a 90° clockwise rotation) of drum 14 of forming conveyor 13, the three pockets 12 supporting the three groups 3 of cigarettes are fed to a transfer station 51 defined between forming conveyor 13 and packing conveyor 19. Between hopper 11 and transfer station 51, there are preferably provided a control station 52 (shown schematically) for checking groups 3 of cigarettes are complete and the tips of cigarettes 4 are filled properly; and a follow-up reject station 53 (shown schematically) where any incomplete groups 3 of cigarettes or groups containing cigarettes 4 with poorly filled tips are rejected. Control station 52 comprises three control devices (not shown) for simultaneously controlling the three groups 3 of cigarettes in the three pockets 12 during a pause, i.e. when each pocket 12 is stationary in front of a respective control device; and similarly, reject station 53 comprises three reject devices (not shown), which can reject any of the three groups 3 of cigarettes in pockets 12 during a pause, i.e. when each pocket 12 is stationary in front of a respective reject device.

Rotating clockwise, an arm 20 of packing conveyor 19 feeds a group of three pockets 22 into transfer station 51. When the group of three pockets 12 is arrested at transfer station 51, the three pockets 12 are arranged in a U to match the arrangement of the three pockets 22, so that each pocket 12 is positioned axially facing and aligned with a respective pocket 22. At this point, a pusher 54 (FIG. 2), having three parallel push members (only one shown in FIG. 2), transfers the three groups 3 of cigarettes from pockets 12 to pockets 22. Pusher 54 performs a back and forth movement, comprising a forward stroke and a return stroke, both parallel to axes of rotation 15 and 21, while the three pockets 22 are stationary in front of the three pockets 12.

Before being fed into transfer station 51, the group of three pockets 22 on packing conveyor 19 is fed through feed station 9 b, where each pocket 22 receives an inner sheet 5 of packing material, which is folded into a tube about pocket 22. Each pocket 22 is preferably in the form of a hollow spindle, on the outside of which an inner sheet 5 of packing material is folded into a tube, and inside which a group 3 of cigarettes is inserted. Feed device 17 only supplies one inner sheet 5 of packing material at a time, and so supplies three sheets 5 of foil packing material successively to the three pockets 22 of a same group of pockets 22. Feed device 17 feeds each inner sheet 5 of packing material to pocket 22 as pocket 22 moves past feed device 17. The movement of each arm 20 is preferably such that a group of three pockets 22 is never arrested in front of feed device 17, but travels at reduced, constant speed past feed device 17. In other words, a group of three pockets 22 is preferably never arrested in front of feed device 17, but travels at reduced, constant speed past feed device 17, on account of feed device 17 being designed to feed each inner sheet 5 of packing material to pocket 22 as pocket 22 is moving.

Once the three pockets 22 have received the three groups 3 of cigarettes at transfer station 51, 180° clockwise rotation of arm 20 of packing conveyor 19 feeds the three pockets 22 supporting the three groups 3 of cigarettes to a transfer station 55 defined between packing conveyor 19 and packing conveyor 25. Between transfer station 51 and transfer station 55, each inner sheet 5 of packing material is folded in known manner about pocket 22.

At the same time, rotating clockwise, an arm 26 of packing conveyor 25 feeds a group of three pockets 28 into transfer station 55. When the group of three pockets 28 is arrested at transfer station 55, the three pockets 28 are arranged in a U to match the arrangement of the three pockets 22, so that each pocket 28 is positioned axially facing and aligned with a respective pocket 22. At this point, a pusher 56 (FIG. 2), having three parallel push members (only one shown in FIG. 2), transfers the three groups 3 of cigarettes from pockets 22 to pockets 28. Pusher 56 performs a back and forth movement, comprising a forward stroke and a return stroke, both parallel to axes of rotation 21 and 27, while the three pockets 28 are stationary in front of the three pockets 22.

Before being fed into transfer station 55, the group of three pockets 28 on packing conveyor 25 is fed through feed station 9 d, where each pocket 28 receives a collar 7, which is folded into a U inside pocket 28. Feed device 23 only supplies one collar 7 at a time, and so supplies three collars 7 successively to the three pockets 28 of a same group of pockets 28. Feed device 23 feeds each collar 7 to pocket 28 as pocket 28 moves past feed device 23. The movement of each arm 26 of packing conveyor 25 is preferably such that a group of three pockets 28 is never arrested in front of feed device 23, but travels at reduced, constant speed past feed device 23. In other words, a group of three pockets 28 is preferably never arrested in front of feed device 23, but travels at reduced, constant speed past feed device 23, on account of feed device 23 being designed to feed each collar 7 to pocket 28 as pocket 28 is moving.

Once the three pockets 28 have received the three groups 3 of cigarettes at transfer station 55, 180° clockwise rotation of arm 26 of packing conveyor 25 feeds the three pockets 28 supporting the three groups 3 of cigarettes to a transfer station 57 defined between packing conveyor 25 and packing conveyor 39. When the group of three pockets 28 is arrested at transfer station 57, the three pockets 28 are aligned with one another in a vertical line.

At the same time, rotating anticlockwise, an arm 40 of packing conveyor 39 feeds a group of three pockets 42 into transfer station 57. When the group of three pockets 42 is arrested at transfer station 57, the three pockets 42 are aligned with one another in a vertical line to match the arrangement of the three pockets 28, so that each pocket 42 is positioned radially facing and aligned with a respective pocket 28. At this point, a pusher 58, having three parallel push members, transfers the three groups 3 of cigarettes from pockets 28 to pockets 42. Pusher 58 performs a back and forth movement, comprising a forward stroke and a return stroke, both perpendicular to axes of rotation 27 and 41, while the three pockets 42 are stationary in front of the three pockets 28.

Before being fed into transfer station 57, the group of three pockets 42 on packing conveyor 39 is fed through feed station 9 f, where each pocket 42 receives a blank 6, which is folded into a U inside pocket 42. Feed device 30 only supplies one blank 6 at a time, and so supplies three blanks 6 successively to the three pockets 42 of a same group of pockets 42. Feed device 30 feeds each blank 6 to pocket 42 as pocket 42 moves past feed device 30. The movement of each arm 40 of packing conveyor 39 is preferably such that a group of three pockets 42 is never arrested in front of feed device 30, but travels at reduced, constant speed past feed device 30. In other words, a group of three pockets 42 is preferably never arrested in front of feed device 30, but travels at reduced, constant speed past feed device 30, on account of feed device 30 being designed to feed each blank 6 to pocket 42 as pocket 42 is moving.

Once the three pockets 42 have received the three groups 3 of cigarettes at transfer station 57, 180° anticlockwise rotation of arm 40 of packing conveyor 39 feeds the three pockets 42 supporting the three groups 3 of cigarettes to a transfer station 59 defined between packing conveyor 39 and drying conveyor 44. Between transfer station 57 and transfer station 59, each blank 6 is folded in known manner about group 3 of cigarettes.

When the group of three pockets 42 is arrested at transfer station 59, the three pockets 42 are aligned with one another in a vertical line, so that each pocket 42 is positioned radially facing and aligned with a respective inlet of a respective conveyor belt 45 of drying conveyor 44. At this point, a pusher 60, having three parallel push members, transfers the three packets 2 of cigarettes containing the three groups 3 of cigarettes from pockets 42 to conveyor belts 45 of drying conveyor 44. Pusher 60 performs a back and forth movement, comprising a forward stroke and a return stroke, both perpendicular to axis of rotation 41, while the three pockets 42 are stationary in front of the three conveyor belts 45 of drying conveyor 44.

The three conveyor belts 45 of drying conveyor 44 feed the three packets 2 of cigarettes containing the three groups 3 of cigarettes to output conveyor 46, which receives the three packets 2 of cigarettes containing the three groups 3 of cigarettes from the three conveyor belts 45, and feeds packets 2 of cigarettes along the single output path. It is important to note that the output path of output conveyor 46 is initially vertical and therefore perpendicular to the three horizontal paths of the three conveyor belts 45, so that, when transferring packets 2 of cigarettes from the three conveyor belts 45 to output conveyor 46, packets 2 of cigarettes are all brought together along a common output path.

As will be clear from the foregoing description, a number of conveyors 13, 19, 25, 39 are provided, each of which has a number of pockets 12, 22, 28, 42 arranged along an endless path and for receiving and conveying respective groups 3 of cigarettes; and groups 3 of cigarettes are transferred from each conveyor 13, 19, 25 to the next conveyor 19, 25, 39 at a transfer station 51, 55, 57 defined between the two conveyors 13, 19, 25, 39. The pockets 12, 22, 28, 42 of each conveyor 13, 19, 25, 39 are divided into a number N1 of (four) groups, each of which comprises the same number N2 of (three) pockets 12, 22, 28, 42; and, at each transfer station 51, 55, 57, a number N2 of (three) groups 3 of cigarettes are transferred simultaneously from the pockets 12, 22, 28 in a given group of pockets 12, 22, 28 on the releasing conveyor 13, 19, 25 to the pockets 22, 28, 42 in a given group of pockets 22, 28, 42 on the receiving conveyor 19, 25, 39.

In the embodiment shown, each group of pockets 12, 22, 28, 42 comprises three pockets 12, 22, 28, 42, so that, at each transfer station 51, 55, 57, three groups 3 of cigarettes are transferred simultaneously. In alternative embodiments not shown, each group of pockets 12, 22, 28, 42 may comprise a different number of pockets 12, 22, 28, 42 greater than one (e.g. two or four).

In the embodiment shown, the conveyors 13, 19, 25, 39 are all rotary, i.e. each comprise a drum 14, 20, 26, 40 supporting the pockets 12, 22, 28, 42 and rotating about a respective central axis 15, 21, 27, 41 to feed the pockets 12, 22, 28, 42 along a circular path. In a different embodiment not shown, forming conveyor 13 and packing conveyor 39 are belt conveyors.

In the embodiment shown, conveyors 13, 19, 25, 39 all comprise a same number N1 of (four) groups of pockets 12, 22, 28, 42, which is common to all of conveyors 13, 19, 25, 39. In a different embodiment not shown, forming conveyor 13 and packing conveyor 39 comprise a number N1 of eight groups of pockets 12 and 42 respectively, and packing conveyor 19 and packing conveyor 25 comprise a number N1 of four groups of pockets 22 and 28 respectively.

In the embodiment shown, pockets 28 of packing conveyor 25 and pockets 42 of packing conveyor 39 are divided into four groups of pockets 28 and four groups of pockets 42; in each group of pockets 28, 42, the central pocket 28, 42 is connected in a fixed position (i.e. rigidly) to packing conveyor 25, 39, while the two lateral pockets 28, 42 are hinged to packing conveyor 25, 39 to rotate between an extracted position at transfer stations 55, 57, 59 and a withdrawn position at feed stations 9 d, 9 f. In the extracted position, pockets 28, 42 of packing conveyor 25, 39 are at least partly extracted with respect to packing conveyor 25, 39, and are aligned with one another in a straight line, whereas, in the withdrawn position, pockets 28, 42 of packing conveyor 25, 39 are positioned tangentially with respect to packing conveyor 25, 29 and therefore aligned in an arc of a circle.

In the embodiment shown, packing conveyors 19, 25, 39 have respective pockets 22, 28, 42, each of which receives a group 3 of cigarettes at a first transfer station 51, 55, 57, releases the group 3 of cigarettes at a second transfer station 55, 57, 59, and receives an inner sheet 5 of packing material, a collar 7, or a blank 6 at a feed station 9 b, 9 d, 9 f having a feed device 17, 23, 30. Each group 3 of cigarettes is transferred to a pocket 22, 28, 42 and is transferred from pocket 22, 28, 42 while pocket 22, 28, 42 is stationary at the first transfer station 51, 55, 57 and second transfer station 55, 57, 59 respectively; whereas, the inner sheet 5 of packing material, collar 7, or blank 6 is transferred to a pocket 22, 28, 42 as pocket 22, 28, 42 travels through feed station 9 b, 9 d, 9 f and is moving with respect to feed device 17, 23, 30. In other words, the movements of conveyors 19, 25, 39 are such that each pocket 22, 28, 42 is arrested at transfer stations 51, 55, 57, 59, but is not stopped at feed station 9 b, 9 d, 9 f, and so travels through feed station 9 b, 9 d, 9 f at substantially constant speed.

As will be clear from the foregoing description, packing conveyor 39 rotates in steps about axis of rotation 41 to feed four groups of packing pockets 42, each having three packing pockets 42, along a packing path. A blank 6 and a group 3 of cigarettes 4 are fed into each packing pocket 42 of a group of packing pockets 42 at feed station 9 f and transfer station 57 respectively, as packing pocket 42 travels through feed station 9 f and, respectively, is arrested at transfer station 57 during a pause between one step and the next. Next, each blank 6 is folded about respective group 3 of cigarettes 4 at the packing station by the corresponding fixed folding member located in a fixed position close to packing conveyor 39. Finally, a group 3 of cigarettes 4, together with respective blank 6, is transferred from each packing pocket 42 of a group of packing pockets 42 at transfer station 59, when packing pocket 42 is arrested at transfer station 59 during a pause between one step and the next. Packing pockets 42 of a group of packing pockets 42 are moved with respect to packing conveyor 39 so that, at transfer stations 57 and 59, the group of packing pockets 42 is set to a transfer position in which packing pockets 42 are aligned with one another in a straight line. Moreover, packing pockets 42 of a group of packing pockets 42 are moved with respect to packing conveyor 39 so that, at the packing station, the group of packing pockets 42 is set to a folding position in which packing pockets 42 are aligned with one another along an arc of a circle coaxial with axis of rotation 41 of packing conveyor 39, thus enabling each blank 6 to be folded about respective group 3 of cigarettes by the fixed folding member.

Packing machine 1 as described above has numerous advantages. In particular, it provides for high output, by performing the packing operations simultaneously on three pockets, while at the same time allowing a relatively long time interval in which to perform each packing operation. As such, each packing operation can be performed extremely accurately, with no need for complicated, untried technical solutions. Moreover, given the step operation of the packing conveyors, packing machine 1 as described above is cheap and easy to produce and set up. This is achieved by means of the particular method of transferring products between two intermittent conveyors, which provides for troublefree transfer of a number of products at the same time.

Given the numerous advantages obtained, the above method of transferring products between two intermittent conveyors may also be applied to other automatic cigarette packing machines (e.g. cellophaning and cartoning machines) or automatic machines for packing other types of products (e.g. confectionary, beverages, and drugs). 

1) A method of transferring a product on an intermittent packing machine; the method comprising the stages of: feeding first pockets (12, 22, 28, 42) of a first conveyor (13, 19, 25, 39) of the intermittent packing machine (1) in steps through a transfer station (51, 55, 57, 59); and transferring at least one product (3) to/from a first pocket (12, 22, 28, 42) of the first conveyor (13, 19, 25, 39) when the first pocket (12, 22, 28, 42) is arrested at the transfer station (51, 55, 57, 59) during a pause between two successive steps; the method being characterized by comprising the further stage, before the product (3) is transferred, of moving the first pocket (12, 22, 28, 42) with respect to the first conveyor (13, 19, 25, 39), so that the first pocket (12, 22, 28, 42) is set to a given transfer position at the transfer station (51, 55, 57, 59). 2) A method as claimed in claim 1, and comprising the further stages of feeding a sheet (5, 6, 7) of packing material to the first pocket (12, 22, 28, 42) at a feed station (9 b, 9 d, 9 f); and folding the sheet (5, 6, 7) of packing material about the product (3) carried by the first pocket (12, 22, 28, 42) at least one packing station. 3) A method as claimed in claim 2, wherein the first pocket (12, 22, 28, 42) is moved with respect to the first conveyor (13, 19, 25, 39) into a transfer position at the transfer station (51, 55, 57, 59), and into a folding position, differing from the transfer position, at the packing station. 4) A method as claimed in claim 3, wherein, in the folding position, the first pocket (12, 22, 28, 42) is positioned tangentially with respect to the first conveyor (13, 19, 25, 39), and, in the transfer position, the first pocket (12, 22, 28, 42) is at least partly extracted with respect to the first conveyor (13, 19, 25, 39). 5) A method as claimed in claim 4, wherein the sheet (5, 6, 7) of packing material is folded about the product (3) by a fixed folding member located, in a fixed position, close to the first conveyor (13, 19, 25, 39). 6) A method as claimed in claim 3, wherein: the first conveyor (13, 19, 25, 39) comprises a rotary body (14, 20, 26, 40) rotating in steps about a central first axis (15, 21, 27, 41) and supporting the first pockets (12, 22, 28, 42); at least two products (3) are transferred simultaneously from/to two first pockets (12, 22, 28, 42) of the first conveyor (13, 19, 25, 39); at the transfer station (51, 55, 57, 59), the two first pockets (12, 22, 28, 42) are arranged flat and are aligned with each other in a straight line; at the packing station (9 c, 9 e, 9 g), the two first pockets (12, 22, 28, 42) are arranged in an arc and are aligned with each other along an arc of a circle coaxial with the central first axis (15, 21, 27, 41); and each sheet (5, 6, 7) of packing material is folded about the product (3) by a fixed folding member located, in a fixed position, close to the first conveyor (13, 19, 25, 39). 7) A method as claimed in claim 1, wherein at least two products (3) are transferred simultaneously from/to two, respectively central and lateral, first pockets (12, 22, 28, 42) of the first conveyor (13, 19, 25, 39). 8) A method as claimed in claim 7, wherein only the lateral first pocket (12, 22, 28, 42) is moved with respect to the first conveyor (13, 19, 25, 39) to set the lateral first pocket (12, 22, 28, 42) to a given transfer position at the transfer station (51, 55, 57, 59). 9) A method as claimed in claim 1, wherein three products (3) are transferred simultaneously from/to three, respectively one central and two lateral, first pockets (12, 22, 28, 42) of the first conveyor (13, 19, 25, 39). 10) A method as claimed in claim 9, wherein only the lateral first pockets (12, 22, 28, 42) are moved with respect to the first conveyor (13, 19, 25, 39) to set each lateral first pocket (12, 22, 28, 42) to a given transfer position at the transfer station (51, 55, 57, 59). 11) A method as claimed in claim 10, wherein the lateral first pockets (12, 22, 28, 42) perform two equal, opposite rotations with respect to the first conveyor (13, 19, 25, 39) as they approach the transfer station (51, 55, 57, 59). 12) A method as claimed in claim 7, wherein the first pockets (12, 22, 28, 42) assume a U-shaped arrangement at the transfer station (51, 55, 57, 59). 13) A method as claimed in claim 7, wherein, at the transfer station (51, 55, 57, 59), the first pockets (12, 22, 28, 42) are positioned flat and are aligned with one another in a straight line. 14) A method as claimed in claim 1, and comprising the further stages of: feeding second pockets (22, 28, 42) of a second conveyor (19, 25, 39) of the intermittent packing machine (1) in steps through the transfer station (51, 55, 57, 59); and transferring the product (3) between the first pocket (12, 22, 28) of the first conveyor (13, 19, 25) and the second pocket (22, 28, 42) of the second conveyor (19, 25, 39) when both the pockets are arrested at the transfer station (51, 55, 57) during a pause between two successive steps. 15) A method as claimed in claim 14, wherein both the first pocket (12, 22, 28) and the second pocket (22, 28, 42) are moved with respect to the corresponding conveyors (13, 19, 25, 39) so as to be positioned facing and aligned with each other. 16) A method as claimed in claim 14, wherein the second pocket (22, 28, 42) is maintained stationary with respect to the second conveyor (19, 25, 39), and only the first pocket (12, 22, 28) is moved with respect to the first conveyor (13, 19, 25) to position the first pocket (12, 22, 28) facing and aligned with the second pocket (22, 28, 42). 17) A method as claimed in claim 14, wherein at least two products (3) are transferred simultaneously from two, respectively central and lateral, first pockets (12, 22, 28) of the first conveyor (13, 19, 25) to two, respectively central and lateral, second pockets (22, 28, 42) of the second conveyor (19, 25, 39). 18) A method as claimed in claim 17, wherein the central first pocket (12, 22, 28) and the central second pocket (22, 28, 42) are positioned facing and aligned with each other at the transfer station (51, 55, 57) without performing any movement with respect to the respective conveyors (13, 19, 25, 39); and the lateral first pocket (12, 22, 28) and lateral second pocket (22, 28, 42) are positioned facing and aligned with each other at the transfer station (51, 55, 57) by moving the lateral pockets (12, 22, 28, 42) with respect to the respective conveyors (13, 19, 25, 39). 19) A method as claimed in claim 14, wherein three products (3) are transferred simultaneously from three, respectively one central and two lateral, first pockets (12, 22, 28) of the first conveyor (13, 19, 25) to three, respectively one central and two lateral, second pockets (22, 28, 42) of the second conveyor (19, 25, 39). 20) A method as claimed in claim 19, wherein the central first pocket (12, 22, 28) and the central second pocket (22, 28, 42) are positioned facing and aligned with each other at the transfer station (51, 55, 57) without performing any movement with respect to the respective conveyors (13, 19, 25, 39); and the lateral first pockets (12, 22, 28) and lateral second pockets (22, 28, 42) are positioned facing and aligned with each other at the transfer station (51, 55, 57) by moving the lateral pockets (12, 22, 28, 42) with respect to the respective conveyors (13, 19, 25, 39). 21) A method as claimed in claim 20, wherein the lateral first pockets (12, 22, 28) perform two equal, opposite rotations with respect to the first conveyor (13, 19, 25) as they approach the transfer station (51, 55, 57). 22) A method as claimed in claim 20, wherein the lateral second pockets (22, 28, 42) perform two equal, opposite rotations with respect to the second conveyor (19, 25, 39) as they approach the transfer station (51, 55, 57). 23) A method as claimed in claim 20, wherein the lateral first pockets (12, 22, 28) perform two equal, opposite rotations with respect to the first conveyor (13, 19, 25) as they approach the transfer station (51, 55, 57); and the lateral second pockets (22, 28, 42) perform two equal, opposite rotations with respect to the second conveyor (19, 25, 39) as they approach the transfer station (51, 55, 57, 59). 24) A method as claimed in claim 14, wherein the first pockets (12, 22, 28) and the second pockets (22, 28, 42) assume a U-shaped arrangement at the transfer station (51, 55, 57). 25) A method as claimed in claim 14, wherein, at the transfer station (51, 55, 57), the first pockets (12, 22, 28) and the second pockets (22, 28, 42) are positioned flat and are aligned with one another in a straight line. 26) A method as claimed in claim 1, wherein the first conveyor (13, 19, 25, 39) comprises a rotary body (14, 20, 26, 40) rotating in steps about a central first axis (15, 21, 27, 41) and supporting the first pockets (12, 22, 28, 42). 27) A method as claimed in claim 1, wherein the first pockets (12, 22, 28, 42) of the first conveyor (13, 19, 25, 39) are divided into a first number (N1) of groups, each comprising a same second number (N2), greater than one, of first pockets (12, 22, 28, 42); and a second number (N2) of products (3) is transferred simultaneously, at the transfer station (51, 55, 57, 59), from/to the first pockets (12, 22, 28, 42) of a same group of first pockets (12, 22, 28, 42) of the first conveyor (13, 19, 25, 39). 28) A method as claimed in claim 27, wherein the first conveyor (13, 19, 25, 39) is rotary, and comprises a member (14, 20, 26, 40) which rotates about a respective central axis (15, 21, 27, 41) to feed its pockets (12, 22, 28, 42) along a circular path. 29) A method as claimed in claim 28, wherein the first conveyor (13, 19, 25, 39) comprises a first number (N1) of groups of pockets (12, 22, 28, 42), rotates in steps about its central axis (15, 21, 27, 41), and, for each step, rotates by an angle equal to a full turn divided by the first number (N1). 30) A method as claimed in claim 27, wherein the first pockets (12) of a same group of first pockets (12) of the first conveyor (13) receive a second number (N2) of products (3) simultaneously from a feed unit (11). 31) A method as claimed in claim 27, wherein the first pockets (42) of a same group of first pockets (42) of the first conveyor (39) release a second number (N2) of products (3) simultaneously to an output unit (44). 32) A method as claimed in claim 27, wherein the first pockets (12, 22, 28, 42) of a same group of first pockets (12, 22, 28, 42) receive respective sheets (5, 6, 7) of packing material at a feed station (9 b, 9 d, 9 f) adjacent to the first conveyor (19, 25, 39) and having a feed device (17, 23, 30). 33) A method as claimed in claim 32, wherein the feed device (17, 23, 30) feeds a single sheet (5, 6, 7) of packing material to a single first pocket (12, 22, 28, 42) as the first pocket (12, 22, 28, 42) travels past the feed device (17, 23, 30). 34) A method as claimed in claim 33, wherein the first pockets (12, 22, 28, 42) of a same group of first pockets (12, 22, 28, 42) are arrested at a transfer station (51, 55, 57, 59) where they receive/release the products (3), and travel at substantially constant speed, without stopping, through a feed station (9 b, 9 d, 9 f) where they receive the sheets (5, 6, 7) of packing material. 35) A unit for transferring a product on an intermittent packing machine comprising a first conveyor (13, 19, 25, 39) having a number of first pockets (12, 22, 28, 42); and a transfer device (54, 56, 58, 60) for transferring at least one product (3) to/from a first pocket (12, 22, 28, 42) of the first conveyor (13, 19, 25, 39) when the first pocket (12, 22, 28, 42) is arrested at a transfer station (51, 55, 57, 59) during a pause between two successive conveying steps; the unit being characterized by comprising an actuating device which, prior to transfer of the product (3), moves the first pocket (12, 22, 28, 42) with respect to the first conveyor (13, 19, 25, 39) to set the first pocket (12, 22, 28, 42) to a given transfer position at the transfer station (51, 55, 57, 59). 36) An intermittent packing machine for packing a product (3) in at least one sheet (5, 6, 7) of packing material; the packing machine (1) comprising: a number of conveyors (13, 19, 25, 39), each having a number of pockets (12, 22, 28, 42) arranged along an endless path and for receiving and conveying at least one respective product (3); and a number of transfer devices (54, 56, 58, 60), each for transferring at least one product (3) to/from a pocket (12, 22, 28, 42) of a respective conveyor (13, 19, 25, 39) when the pocket (12, 22, 28, 42) is arrested at a transfer station (51, 55, 57, 59) during a pause between two successive conveying steps; the packing machine (1) being characterized in that, on each conveyor (13, 19, 25, 39), the pockets (12, 22, 28, 42) are divided into a first number (N1) of groups, each comprising a same second number (N2), greater than one, of pockets (12, 22, 28, 42); each transfer device (54, 56, 58, 60) simultaneously transfers a second number (N2) of products (3) to/from the pockets (12, 22, 28, 42) of a same group of pockets (12, 22, 28, 42) of a respective conveyor (13, 19, 25, 39); and each group of pockets (12, 22, 28, 42) of at least one conveyor (13, 19, 25, 39) comprises an actuating device which, prior to transfer of the product (3), moves at least one of the pockets (12, 22, 28, 42) with respect to the conveyor (13, 19, 25, 39) to set the pocket (12, 22, 28, 42) to a given transfer position at the transfer station (51, 55, 57, 59). 37) A packing machine as claimed in claim 36, wherein at least one conveyor (13, 19, 25, 39) is rotary, and comprises a member (14, 20, 26, 40) which rotates about a respective central axis (15, 21, 27, 41) to feed its pockets (12, 22, 28, 42) along a circular path. 38) A packing machine as claimed in claim 37, wherein the rotary conveyor (13, 19, 25, 39) comprises a first number (N1) of groups of pockets (12, 22, 28, 42), rotates in steps about its central axis (15, 21, 27, 41), and for each step, rotates by an angle equal to a full turn divided by the first number (N1). 39) A packing machine as claimed in claim 38, wherein the rotary conveyors (13, 19, 25, 39) all comprise a same first number (N1) of groups of pockets (12, 22, 28, 42), which is common to all the rotary conveyors (13, 19, 25, 39); and, for each step, the rotary conveyors (13, 19, 25, 39) all rotate by a same angle equal to a full turn divided by the first number (N1). 40) A packing machine as claimed in claim 36, and comprising a feed unit (11) for simultaneously transferring a first number (N1) of products (3) to the pockets (12) of a same group of pockets (12) of a start conveyor (13). 41) A packing machine as claimed in claim 40, wherein the feed unit (11) comprises a second number (N2) of outlets, each of which transfers a product (3) to a respective pocket (12) of the start conveyor (13). 42) A packing machine as claimed in claim 36, and comprising an output unit (44), which simultaneously receives a second number (N2) of products (3) from the pockets (42) of a same group of pockets (42) of an end conveyor (39). 43) A packing machine as claimed in claim 42, wherein the output unit (44) comprises a second number (N2) of output paths, which are parallel to one another, and each of which receives a product (3) from a respective pocket (42) of the end conveyor (39). 44) A packing machine as claimed in claim 36, for packing a group (3) of cigarettes in an inner sheet (5) of packing material, and in an outer sheet (6) of packing material; the packing machine comprising: a hopper (11) having a second number (N2) of outlets; a drum-type first forming conveyor (13) comprising a first number (N1) of groups of first pockets (12), each comprising a second number (N2) of first pockets (12); a first transfer device (50) for simultaneously transferring a second number (N2) of groups of cigarettes to the first pockets (12) of a same group of first pockets (12) of the first forming conveyor (12); a drum-type second packing conveyor (19) comprising a first number (N1) of groups of second pockets (22), each comprising a second number (N2) of second pockets (22); a second transfer device (54) for simultaneously transferring a second number (N2) of groups of cigarettes from the first pockets (12) of a same group of first pockets (12) of the first forming conveyor (13) to the second pockets (22) of a same group of second pockets (22) of the second packing conveyor (19); a drum-type third packing conveyor (25) comprising a first number (N1) of groups of third pockets (28), each comprising a second number (N2) of third pockets (28); a third transfer device (56) for simultaneously transferring a second number (N2) of groups of cigarettes from the second pockets (22) of a same group of second pockets (22) of the second packing conveyor (19) to the third pockets (28) of a same group of third pockets (28) of the third packing conveyor (25); a drum-type fourth packing conveyor (39) comprising a first number (N1) of groups of fourth pockets (42), each comprising a second number (N2) of fourth pockets (42); a fourth transfer device (58) for simultaneously transferring a second number (N2) of groups of cigarettes from the third pockets (28) of a same group of third pockets (28) of the third packing conveyor (25) to the fourth pockets (42) of a same group of fourth pockets (42) of the fourth packing conveyor (39); a drying unit (44) having a second number (N2) of output paths; and a fifth transfer device (60) for simultaneously transferring a second number (N2) of groups of cigarettes from the fourth pockets (42) of a same group of fourth pockets (42) of the fourth packing conveyor (39) to the output paths of the drying unit (44). 45) A packing machine as claimed in claim 44, wherein the drying unit (44) comprises a second number (N2) of conveyor belts (45), which are straight, are parallel to one another, and define the output paths. 46) A packing machine as claimed in claim 44, and comprising a first feed device (17) located along the periphery of the second packing conveyor (19) to feed a first sheet (5) of packing material to each second pocket (22) of the second packing conveyor (19). 47) A packing machine as claimed in claim 46, wherein the first feed device (17) feeds a single first sheet (5) of packing material to a single second pocket (22) of the second packing conveyor (19) as the second pocket (22) travels past the first feed device (17). 48) A packing machine as claimed in claim 44, and comprising a second feed device (30) located along the periphery of the fourth packing conveyor (39) to feed a second sheet (6) of packing material to each fourth pocket (42) of the fourth packing conveyor (39). 49) A packing machine as claimed in claim 48, wherein the second feed device (30) feeds a single second sheet (6) of packing material to a single fourth pocket (42) of the fourth packing conveyor (39) as the fourth pocket (42) travels past the second feed device (30). 50) A method of packing a product (3) in a sheet (6) of packing material, and comprising the stages of: rotating a packing conveyor (39) in steps about a first axis of rotation (41) to feed at least one group of packing pockets (42) along a packing path; feeding a sheet (6) of packing material and a product (3) into each packing pocket (42) of the group of packing pockets (42) at least a first transfer station (57), when the packing pocket (42) is arrested at the first transfer station (57) during a pause between two successive steps; folding each sheet (6) of packing material about the respective product (3) at least one packing station; and transferring a product (3), together with the respective sheet (6) of packing material, from each packing pocket (42) of the group of packing pockets (42) at a second transfer station (59), when the packing pocket (42) is arrested at the second transfer station (59) during a pause between two successive steps; the method being characterized by comprising the further stages of: moving the packing pockets (42) of the group of packing pockets (42) with respect to the packing conveyor (39) so that, at the transfer stations (57, 59), the group of packing pockets (42) is set to a transfer position in which the packing pockets (42) are aligned with one another in a straight line; moving the packing pockets (42) of the group of packing pockets (42) with respect to the packing conveyor (39) so that, at the packing station, the group of packing pockets (42) is set to a folding position in which the packing pockets (42) are aligned with one another along an arc of a circle coaxial with the first axis of rotation (41) of the packing conveyor (39); and folding each sheet (6) of packing material about the respective product (3) at the packing station (9 g) by means of a fixed folding member located, in a fixed position, close to the packing conveyor (39). 51) A method as claimed in claim 50, wherein the packing pockets (42) of the group of packing pockets (42) are moved with respect to the packing conveyor (39) by rotating about respective second axes of rotation (43) parallel to the first axis of rotation (41). 52) A method as claimed in claim 50, wherein each sheet (6) of packing material is fed to the respective packing pocket (42) before the product (3) is fed to the same packing pocket (42). 